I love mixing up my paper kits and using them in unexpected ways. It's a little trickier in Studio J, but definitely doable.
This first layout uses the Studio J-exclusive Halloween paper kit called BOO. You can't even tell it's Halloween-themed from my layout.
These are the papers in the BOO kit. Plus, you can use any color cardstock and you can use the "backs" of the papers for a lighter tone in one of the patterns.This second layout uses another Studio J-exclusive paper pack called Class Act. As you can guess, it's a back-to-school theme.
Here are the papers in Class Act. I also pulled in some Crystal Blue with the cardstock, a color that doesn't come in the paper kit. But it works nicely with the papers I chose.
When using seasonal kits in Studio J, you'll find that most of the stickers are seasonal and probably won't work for your "normal" layout. In both of my layouts I found some star stickers to use, along with brads and buttons, but most of the other stickers were school- and Halloween-related. If you want a little more embellishing on your layout, just add some "real" embellishments once you get the prints! It'll add some nice dimension and you'll be able to use up some of your stash :)
You can play with Studio J here (it's free to try it out).